The invention relates to peptides and peptide derivatives based on the naturally occurring peptide xenin. The invention provides a peptide of SEQ ID No. 1 or an analogue thereof which is able to stimulate insulin secretion and which has no more than 7 amino acid substitutions or deletions as compared to the native sequence, the peptide having one or more lysine residues substituted with a lipophilic substituent of 840 carbon atoms, optionally via a spacer. The present invention also provides a peptide of SEQ ID No. 1 or an analogue thereof which is able to stimulate insulin secretion and which has no more than 7 amino acid substitutions or deletions as compared to the native sequence and in which one or more of Lys4, Lys8, Arg11, Lys13, Phe17, Lys20, or Arg21 have been replaced with another amino acid which increases resistance of the peptide to enzymatic degradation. Further provided are molecules and formulations comprising these peptides and therapeutic uses of these peptides.
